Light Detection and Ranging (LiDAR) is a sensing method that uses a light beam to measure the distance to various objects. A LiDAR sensor works by emitting a light beam and measuring the time it takes to return. The return time for each return light beam is combined with the location of the LiDAR sensor to determine a precise location of a surface point of an object, and this location is recorded as a three-dimensional point in space. An optical camera captures and records images of the external environment. A camera works by opening an aperture to take in light through a lens, and then a light detector (e.g., a charge-coupled device (CCD) or CMOS image sensor) turns the captured light into electrical signals including color and brightness of each pixel of the image.
Autonomous vehicles typically use a LiDAR sensor to obtain depth profiles of the environment, and an optical camera to obtain image profiles of the environment in order to help navigate the vehicle around the environment. However, because the LiDAR sensor is placed next to a separate imaging sensor, data from the LiDAR sensor must be calibrated and aligned with the data from the imaging sensor. In addition, problems with alignment may arise due to the distance between the position of the LiDAR sensor and the position of the imaging sensor and changes in thermal amplitudes over the course of the day in each of the components. Moreover, both components may be prone to drift and calibration errors caused by vibrations inherent in vehicular movement.